In order to obtain the influence of gas-liquid nozzle and acoustic resonators on the acoustic characteristics of combustion chamber and explain the mechanism of tangential frequency differentiation in acoustic experiments

a model combustion chamber with cylindrical tubes was investigated by acoustic finite element method (FEM). The analysis results were verified by the experiment of a single injector chamber. On this basis

the influence rules of gas nozzle

orifice and resonators on acoustic frequency were established in terms of the frequency and sound pressure distribution. The phenomenon of frequency differentiation was explained by the sound pressure distribution results. Results showed that the energy of tangential mode transferred into the gas nozzle and changed the original mode of combustion chamber

when the frequency of first order longitudinal mode of gas nozzle or resonator was equal to that of the tangential mode of combustor

and the phenomenon of frequency differentiation in tangential modes emerged in acoustic experiments. The coupling relationship between gas nozzle length and diameter of orifice was discovered

enabling to make combinatorial parameter optimization during rocket engine design.